Yes, according to Panasonic this works:
USB slot: Yes
Front playback
USB Standard: USB 2.0 High Speed
Playback: Xvid/ MKV/ MP4/ MPEG-2/ FLAC/ WAV/ WMA/ AAC/ MP3/ ALAC/ DSD/ JPEG/ MPO
The hard disk is only used as storage for firmware updates, nothing can be stored on it :-)
No, does not belong to the compatible devices: https://www.focus.de/shopping/service/streaming-dienst-disney-wie-sie-disney-empfangen-koennen-alle-geraete-im-ueberblick_id_11817084.html
Which home cinema do you own? Is only the actual player broken (i.e. drive) or the whole sound system?
It is not possible to connect speakers directly here. This is normally connected to your home cinema via HDMI.